About This Episode
Mark Roberts, senior waste planning specialist at Auckland Council (10 years), delivers the podcast's most data-rich episode on construction waste. The numbers are staggering: 35-40% of Auckland landfill waste comes from construction, rising to 80% of nationwide waste when soil is included; half a million tons per year goes to Auckland landfill alone; and a typical 200sqm 4-bedroom house generates 3.7 tons of waste. His key insight, "waste is designed into buildings", reframes the problem: it starts with architects and quantity surveyors, not builders on site. The conversation covers the invisibility of construction waste (high-sided skip bins, fenced sites), Flatbush as a worst-case example of littering and illegal dumping, "The Great Skip Dive" audit (2022), and the need to work upstream with designers and specifiers rather than blaming builders.
Key Topics Discussed
- Construction waste statistics:
- 35-40% of Auckland landfill waste is from construction
- With soil: 80% of nationwide waste is construction and demolition related
- Household waste is approximately 20% vs construction at 35% (construction nearly double household)
- Half a million tons per year going to landfill in Auckland alone
- 3.7 tons of waste per typical 200sqm 4-bedroom house build
- Three types of fills. Landfill, clean fill, managed fill (biosolids); each with different regulatory requirements
- Invisible waste. Construction waste is hidden: high-sided skip bins, fenced sites, transported unseen; "out of sight, out of mind"
- Flatbush as worst example. Littering, poor waste management, illegal dumping, poor sediment control; "those things are all friends"
- "Waste is designed into buildings". The key insight: waste starts with design, gets specified into buildings, and is quantity surveyed in; the problem originates upstream, not on site
- "Stop blaming builders". Builders are dealing with the hand they have been dealt; architects and QSs need to design waste out
- The Great Skip Dive (2022). Audited waste from two typical house builds; found timber, metal, tiles, over-ordered materials
- 10 local board projects. Across Auckland focused on construction waste behaviour at the community level
- Working upstream. Engaging NZ Institute of Architects and Institute of Quantity Surveyors to address waste at the design stage
- Blair Chant and Nailove. Mentioned as innovative approaches to waste reduction in construction
- Council's role. Shine light on the problem, build relationships, fund research, encourage innovation
- Waste sorting infrastructure. Two large co-mingled waste sorting facilities in Auckland
Notable Quotes
"Waste is designed into buildings.", Mark Roberts on why the problem starts at the drawing board, not on site.
"Stop blaming builders, they're dealing with the hand they've been dealt."
Construction waste is "out of sight, out of mind", hidden behind high-sided skip bins and fenced sites.
3.7 tons of waste per typical 200sqm 4-bedroom house build.
Guest Background
Mark Roberts is a senior waste planning specialist at Auckland Council where he has worked for 10 years. Before council he spent 10 years at Sustainable Business Network, has 20 years in IT, and holds a Masters in resource efficiency. His cross-sector background gives him a unique systems-level view of construction waste.
